1. Field of the Invention
The present invention pertains to a power supply unit used in an image forming device such as a copier or printer, and more particularly to a power supply unit that supplies power to an induction heat fusing apparatus of an image forming device.
2. Description of the Related Art
Due to their simplicity of construction and low cost, halogen lamps are often used as the heat source for the fusing apparatus used in an image forming device such as a copier or printer using the electrophotographic method. However, halogen lamps have the problem that they take a long time to warm up. To solve this problem, a fusing apparatus based on a method using induction heat (induction heat fusing method) has been proposed.
Using this fusing apparatus based on the induction heat fusing method, the heating process takes a relatively short period of time. In this sense, it has an energy saving effect that the heating need not be performed beyond the necessary time. On the other hand, however, an inverter to perform high frequency switching of electric current is necessary.
Image forming devices such as copiers or printers using the electrophotographic method depend on multiple power supply units such as a power supply to provide power to the motors that drive the elements of the image forming device, and a power supply to provide power to the controller (microcomputer) that controls the operations of the elements of the image forming device. If an inverter power supply needed for the induction heat fusing device were separately added to these power supply units already in existence, reduction in size or cost of the image forming device would be hindered.